A psychologist has taken to TikTok this week to share an incredible optical illusion that has left social media users baffled.
Dr. Julie Smith, a psychologist with a practice in Ringwood in Hampshire, took to the social media platform to post a bizarre clip demonstrating how viewers watching can trick their brains into seeing color when there isn't any.
The video opens in monochrome, with Dr. Smith sitting down in her backyard with a white cross superimposed on her forehead.
Take a look at the mind-bending footage right here:It then changes from black and white to saturated color, with Smith's face now looking like something from a photo negative, while the color of the cross goes from white to black.
But this effect wasn't caused by video editing or camera filters. Instead, as Dr. Smith explains, it's all down to overexposing receptors in the human eyes to certain colors in the light spectrum.
This in turn forces our brain to invert the colors our brain perceives when the black and white image first appears.
As a result, when the video switches back to monochrome, it appears to be brighter and more vivid.
The video has since picked up a lot of traffic on the platform, accruing over 739,000 views, 171,000 reactions, and a further 4,400 comments from other bemused TikTok users as of the time of writing.
For instance, one commenter wrote: "It worked for me till I looked away from the cross on the playback."
Another person added that they could see: "Purple flowers, blue bench, green behind you and your shirt looks green."
But another person joked that they couldn't make head or tails of the footage, writing: "Uh oh. I think my brain is broken."
Someone else agreed, stating: "That freaked me out so bad! As long as I kept focusing on the x I saw color for almost the entire black and white part."
This person then stated that the image changed colors, writing: "For a second but it was really dulled out."
Another added: "Everything but the floor was color. I saw color when you started talking about it."
Lastly, this commenter stated: "Had to watch it through twice, worked for [the] second time for a split second! Pretty cool. [sic]"
Dr. Smith herself later took to the comments to tell people who hadn't managed to experience the illusion first time how they could have a second go, writing, "PRO TIP: if you can't see it: Don't move your eyes around the image.
"Keep focusing on the cross even when the video goes to black and white again. [sic]"